Ensuring the Persistence of Array Manipulations in JavaScript Functions

Question

Ensuring the Persistence of Array Manipulations in JavaScript Functions

I've been working on a JavaScript function in ES5 that is designed to take an array, filter it, and then assign the original array with the filtered results.

If you'd like to check out my progress so far, feel free to visit my plunk here.

Here is a rough outline of what I'm attempting to achieve:

var result = [{ 'date': '20171116' }, { 'date': '20171115' }];
var data = { 'date': '2017116' };
deleteEntry(data, result);
console.log(result); // should have one entry

function deleteEntry(data, result) {
  result = result.filter(function(item) {
    return item.date !== data.date;
  });
}

I suspect that the issue lies within how arrays are referenced. If anyone has any insights on how to tackle this problem, I would greatly appreciate it.

javascript arrays reference ecmascript-5

Answer 1

Answer №1

Make sure to update the array with the changes and store it in a variable called result:

function removeEntry(inputData, result) {
  return result.filter(function(entry) {
    return entry.date !== inputData.date;
  });
}

result = removeEntry(inputData, result);

Answer 2

Make sure to update the array with the changes and store it in a variable called result:

function removeEntry(inputData, result) {
  return result.filter(function(entry) {
    return entry.date !== inputData.date;
  });
}

result = removeEntry(inputData, result);

Answer 3

Answer №2

When using Array.filter, it's important to note that it returns a new array instance. This means that when you assign the result of filter back to itself (e.g. result = result.filter(...)), you lose the reference to your original array. A better alternative in this case would be to use array.splice instead:

var result = [{ 'date': '20171116' }, { 'date': '20171115' }];
var data = { 'date': '20171116' };
deleteEntry(data, result);
function deleteEntry(data, result) {
    var index = result.findIndex(item => item.date === data.date);
    result.splice(index, 1);
}
console.log(result);

Answer 4

When using Array.filter, it's important to note that it returns a new array instance. This means that when you assign the result of filter back to itself (e.g. result = result.filter(...)), you lose the reference to your original array. A better alternative in this case would be to use array.splice instead:

var result = [{ 'date': '20171116' }, { 'date': '20171115' }];
var data = { 'date': '20171116' };
deleteEntry(data, result);
function deleteEntry(data, result) {
    var index = result.findIndex(item => item.date === data.date);
    result.splice(index, 1);
}
console.log(result);

Answer 5

Answer №3

If you want to replace all elements in an array based on a certain condition, you can utilize the Array#splice method.

function replaceEntries(data, result) {
    Array.prototype.splice.apply(result, [0, result.length].concat(result.filter(function(item) {
        return item.date !== data.date;
    })));
}

var result = [{ date: '20171116' }, { date: '20171115' }],
    data = { date: '20171116' };
    
replaceEntries(data, result);
console.log(result);

In ES6:

function replaceEntries(data, result) {
    var temp = result.filter(item => item.date !== data.date);
    result.length = 0;
    result.push(...temp);
}

var result = [{ date: '20171116' }, { date: '20171115' }],
    data = { date: '20171116' };
    
replaceEntries(data, result);
console.log(result);

Answer 6

If you want to replace all elements in an array based on a certain condition, you can utilize the Array#splice method.

function replaceEntries(data, result) {
    Array.prototype.splice.apply(result, [0, result.length].concat(result.filter(function(item) {
        return item.date !== data.date;
    })));
}

var result = [{ date: '20171116' }, { date: '20171115' }],
    data = { date: '20171116' };
    
replaceEntries(data, result);
console.log(result);

In ES6:

function replaceEntries(data, result) {
    var temp = result.filter(item => item.date !== data.date);
    result.length = 0;
    result.push(...temp);
}

var result = [{ date: '20171116' }, { date: '20171115' }],
    data = { date: '20171116' };
    
replaceEntries(data, result);
console.log(result);

Ensuring the Persistence of Array Manipulations in JavaScript Functions

Answer №1

Answer №2

Answer №3

Similar questions

Hiding the style tag in the head section of a Laravel-Vue.js application with Vue.js

Having trouble making an ajax request using Cordova?

How can I incorporate "Context" into route configuration?

Determine the size of a multidimensional array in C using the scanf

Utilizing Python with Selenium to address the "ElementNotVisibleException" by employing the "execute_script" method

What causes the z-index value to stay the same even after it has been modified using the .css() function?

Is it possible to align an image that uses position:relative with one that uses position:absolute?

Searching for specific values within a multidimensional array using PHP

Executing ws.send from the controller in a Node.js environment

dynamic array within a large matrix

What is the best way to switch between two components using vue.js?

What is the best way to retrieve the object of the selected option from a single select input in Angular

What is the best way to use JavaScript to locate and interact with a button on a webpage based on its XPath and the text it contains?

Tips for efficiently submitting data to multiple child components without causing unnecessary re-renders

NodeJS Issue: Failure to Save Record in Parse

Yearly Grouping with MongoDB's Aggregate Framework

data retrieval not refreshing sorting post construction

Sending form data to the server using JavaScript: A step-by-step guide

Exploring the insights into React-hook-form Controller

The Google analytics page tracking feature is experiencing issues within an AngularJS application and is not functioning correctly